Permutation lock



.A.F.1Acos`oN.

' PERMUTATION LOCK.

APPLICATION FILED JUNE l0, 1921.

L42?, m6, Patented Aug. 29, 1922.

r l ff Le l ATTORNEY.

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C j .ARTHUR r. JAGOBSON, or Dnfrnorr, MICHIGAN. y

Lazl. y L1 Application med June 1o,

To all whom t may concern.'

Be it known that l, ARTHURv F. JAoossoN, a citizen of the United vStates, residinsT at Detroit, in the county of Tayne and tate of Michigan, have invented certain new and useful Improvements in Permutation Locks, of which the following is a specification.

This invention Y relates to permutation locks, and has for its object a permutation. lock provided with a knoby which is a piece separate from the spindle ,and the numeral disk. This knob is connected with the spindle and niuneral disk by a concealed but fragile connection.

A greatmany safes are opened by the socalled yeggmen or safe-breakers simply by striking the knob with a suitable tool until the numeral disk and spindle are knocked off the door, giving access to the notched disks inside. This permits the safe-breaker to line up the notches in the disk to permit the tumblers to drop in, the bolts shot, and the safe opened. Even if the yegg does not gain access to the safe he very often jimmies the lock mechanism so as tov require a new lock or so that the safe cannot be opened except by an expert.

It is the object of the present invention to provide a construction which will permit the knob to be easily broken oli even with the face of the numeral disk so that the yeggman is frustrated in his attempt to pry the disk and the spindle out or to injure the inner mechanism of the lock.

In the drawings,-

Fig. l is a front elevation of the lock.

Fig. 2 is a fragmentary section showing only the numeral disk and a part of the spindle together with the knob and the fragile connection.

a designates the ordinary numeral disk that is used on a safe. b is the knob. The face of this disk a at the center is provided with a nicely machined portion to receive the knob b which has its corresponding face nicely machined to fit tightly onto a similar surface of the numeral disk. The numeral disk is bored and tapped at its center, as is also the knob. However, the knob is only bored part way in from the rear face and the numeral disk only part way in from the front face. This permits a fragile threaded stud c to be turned into the knob and then the stud turned into the threads ofthe numeral disk or the knob turned onto `Speeeaton of Letters Patent.

PERMUTATTON LOCK. l

Patented Aug. 5259., 1922.

1921'. Serial. No. 4765378.

the threads of the studif the' studhas been .first located in the numeral fdisk. This stud'is provided with a weakened portion or a portion of reduced diameterv x arranged to come at the dividing line of the knob and numeral disk. The knob may then be turned down very tightly on the numeral disk. vThere is also provided some means for flocking the knob from turning off from the threaded stud.` T find` that a very convenient and blind wayy of locking the knob to the numeral disk is to provide a plurality of small sockets (Z in the numeral disk and provide a single pin perfora' tion e in the base of the knob. The knob can be turned down tightly to bring the pin perforation in registry with one of these sockets cl. A pin f may then be driven in and filed or finished ofi" on the top so it is practically unseen. This forms a lock to prevent the knob from backing off the stud.

The stud is made of vsome highly fragile metal, such as some of the hardened steels that have very little resistance to a fracture. There are numerous alloys or metals that can be used to provide a suitable stud which at the same time will be easily fractured when the knob is subjected to a heavy blow.

Tt will be obvious when a safe-breaker strikes the knob with a heavy blow that the knob will separate from the disk, the stud breaking in two at the reduced portion a and thereby leaving the numeral disk and the inner mechanism unharmed. The knob having been broken off at the dividing line of the knob and disk, there will be no surface left for the safe-breaker to apply a tool and pry the disk out and thereby the attempt to get at the inner mechansm of the lock will be frustrated. Furthermore, no hole will be left in the numeral disk in which a charge of explosive may be sealed by beeswax or the like to shatter the lock7 when exploded. l

In the claims the disk is spoken of as the numeral disk as a descriptive designation. Obviously the numerals might be on the ringin which the disk revolves and the disk would not then be strictly a numeral disk but I want it understood that such a disk would come within my invention.

What l claim is:

l. In a permutation lock, a numeral disk provided with a tapped central opening and a knob provided with a'tapped central opening at its back, and a threaded fragile stud for holding the knob to the numeral disk.

2. In a permutation' lock', the combination of a numeral disk, a knob separate from the numeral disk, and a 'fragile stud for securing the numeral disk and the knob together, same fragile stud let into the knob from the rear and concealed at the front of the knob.

3. In a permutation look,v theeombinationof a numeral disk, ya knob separately formed, threaded stud 'for securing `the knob ,to the numeral disk, said numeral disk beingprovided: vwithva plurality of pin sockets and the said base of the knob provided with a pin perforation which caribe caused to register with one of the pin sockets when the knob has been turned down tightly uponfthe threaded stud, anda pin in the registering perforation and socket for looking `the knob romirotation to prevent the and lprovided with a redueed .weakened portion near the face of the diskwvhieh will allow ithe stud to fracture ;on thedivision line-between k-'nob andfnumeral -diskwhenV :subjected ht0 unusual Stress.-

f' ln testimony whereoi2 I "aixi my signaf ture.

vAmmin F; JiioOBsoN. 

